It is known to provide priority valves having two inlets for fluid under pressure and a single outlet and in which there is a valve element movable by fluid pressure between the two inlet ports for connecting the outlet port with whichever inlet port has the highest pressure therein and for closing off the outlet port from the other inlet port. Such valves usually have a valve element in the form of either a ball, as in U.S. Letters Pat. No. 2,627,388 or a piston, as in U.S. Letters Pat. No. 2,206,957.
In such prior priority valves, the effective area for sensing the differential in pressure between the two inlet ports is equal to the area of the port being closed off and may not provide enough seating force to effectively close the inlet port with the lower pressure.